1. Field of the Invention
The present invention relates to an image recording apparatus. More particularly, the present invention relates to a device for calculating a sheet number of recording papers piled up on an automatic sheet feeder (ASF) in an image recording apparatus and a method for calculating the same.
2. Description of the Prior Art
An image recording apparatus, such as a wire dot printer, a thermal printer, or ink jet printer, includes a unique recording head for recording image data on a recording medium such as a recording paper or overhead projector (OHP) film. These recording apparatuses generally include automatic sheet feeders guides to assure proper feeding of the recording papers through the apparatus. Conventional automatic sheet feeders typically do not apprize the user as to the number of sheets piled thereon. When the recording apparatus has print jobs which would exhaust the number of papers in the feeder, the user typically discovers same upon returning to collect the jobs after a sufficiently long period of time deemed necessary to complete the job and must re-supply the increasing the time needed to get the job done.
Several types of sheet feeding apparatus are disclosed in the patent literature. Unfortunately, the apparatuses described do not provide the features in the convenient simple manner of the preset invention does. For example, U.S. Pat. No. 4,503,960, issued Mar. 12, 1985, to G. A. A. Koeleman, describes a Method and Apparatus for Sensing a Supply of Sheets in a Magaziue. Referring to FIG. 1, the device includes a height sensor 1 which ascertains the height of a stack of sheet by unknown means. An equally unknowable calibration element 3 applies a conversion factor to the height signal to convert the height signal into a number of sheets.
U.S. Pat. No. 5,599,014, issued Feb. 4, 1997, to Y. Kitahara et al., describes a Sheet Conveyor Apparatus. Referring to FIG. 2 and column 4, lines 1-9, the device includes sheet thickness sensors 75a and 75b, each employing an optical sensor of the permeable type. Referring to lines 10-17, the thickness detector only ascertains and produces a signal for either a thick or thin sheet.
U.S. Pat. No. 5,145,163, issued Sep. 8, 1992, to K.P. Cowan et al., describes a Film Sheet Mode Magazine. Referring to FIG. 5 and column 7, lines 45-69, the device employs a primary feed roller 48 having a drive shaft which contacts a lever member 134. A pointer 130 is fixed to the lever member 134. The pointer corresponds to a thickness of films 12 relative to a sheet feeder bed and indicates same unremovable scale. Different scales may be substituted corresponding to estimated empirical thicknesses attributed to the sheet stock maintained in the sheet feeder.
U.S. Pat. No. 5,097,496, issued Mar. 17, 1992, to H. Madate, describes a Sheet Extracting Mechanism with Function for Detecting the Amount of Stacked Sheets and Recording Systemn Utilizing the Same. Referring to FIG. 1and column 4, lines 5-10, the film amount detecting mechanism detects a position where a suction cup picks up film stock and compares the measurement to a calibrated position where the suction cup would not be able to pick up a film stock.
U.S. Pat. No. 5,011,128, issued Apr. 30, 1991, to K. Tsuji, describes an Apparatus for Detecting the Thickness of Sheets. Referring to FIG. 1and column 7, lines 63-68, the invention includes an auxiliary roller 11, abutting against the movable roller 3, mounted on a detecting arm 12. The detecting arm is mounted to an angle sensor 13. The mechanics of the angle sensor are not disclosed.
U.S. Pat. No. 4,729556, issued Mar. 8, 1988, to K. Fujii et al., describes an Apparatus for Detecting the Thickness of Bank Notes. Referring to FIG. 1and column 3, lines 49-63, the device includes a detection roller 17 which is pushed upward when a sheet is received thereunder, rotating the detection arm 16 counterclockwise, actuating a potentiometer 23.
U.S. Pat. No. 4,734,747, issued Mar. 29, 1988, to M. Okuda et al., describes a Copying Machine with a Copy Paper Detection Device. Referring to FIG. 6 and column 6, lines 56-68, the device includes a light emitting element 52 and five light detecting elements 53a-53e. As the paper supply 55 diminishes, more sensors are exposed to light.
U.S. Pat. No. 4,835,573, issued May 30, 1989, C. Rohrer et al., describes a Machine Control System Utilizing Paper Parameter Measurements. Referring to FIG. 1and column 5, lines 33-68, the device includes an elevator mechanism in a copy supply bin 20 and an elevator motor 30, including a tachometer, to raise and lower the elevator. The paper supply bin also has a limit switch which is tripped by a stack of paper. Rohrer et al. describes calculating the sheet thickness by converting the output of the tachometer as sheets are removed and counted, and the elevator is elevated to maintain the sheets at a constant level.
U.S. Pat. No. 4,627,715, issued Dec. 9, 1989, to M. Kikuno, Describes a Programmable Copier. Referring to FIG. 5 and column 3, lines 7-20, the device includes three sets of light detectors 10a-10c, positioned at different heights within a sheet feeder bin.
U.S. Pat. No. 4,662,816, issued May 5, 1987, to P. Fabrig, describes a Method of Breaking up Stacks of Paper Sheets or the Like. Referring to FIG. 1and column 8, lines 34-62, the device includes a means 55 for monitoring thickness, including a reciprocal ram that is coupled to any of a number of dial gages, which may be changed depending on a predetermined notion of sheet thickness.
U.S. Pat. No. 4,462,587, issued Jul. 31, 1984, to H. T. Graef et al., Describes a Method of and System for Detecting Bill Status in a Papers Money Dispensing Machine. Referring to FIGS. 8A-8B and column 10, lines 21-34, the device includes electronic sensors 62 having rollers 60 in contact with rolls 56, 58, 54 or 52 of the apparatus. Paper or bills are not received between the sensor roller 60 and contacting roller 56, 58, 54 or 52.
U.S. Pat. No. 4,373,135, issued Feb. 8, 1983, to W. L. Mohan et al., describes a Pitch Matching Detecting and Counting System. Referring to FIG. 7 and column 5, lines 3-24, the device includes a single sensor 102 positioned relative to a stack of similar objects 104 and a light source 106. The light source is focused by a condensing lens 110 on the edges of the stack objects to form an illuminated area 112. The width of the slit formed between the masks is adjusted by positioning a pitch match dial 118, the width of the paper being ascertained therefrom.
U.S. Pat. No. 3,826,487, issued Jul. 30, 1974, to K. Forster et al., describes a Control Apparatus and Method for Transporting Sheets. Referring to FIGS. 3-6, and column 3, the device includes a magnitude sensor 8 having a transducer 9 mounted thereon. As the sensor is strained, the transducer generates a signal corresponding to the sheet thickness. Alternatively, referring to FIG. 5, the device may include a sensor 8" with a sensing piston 34 that contacts the sheets. The rear portion 34a of the sensing piston interrupts a light beam issued from a light source 36 toward a photoelectric matrix 35.
U.S. Pat. No. 3,778,051, issued Dec. 11, 1973, to J. H. Allen et al., describes a Superposed Sheet Detector. Referring to FIG. 1and column 3, line 60 through column 4, line 7, the device includes a transducer 101 adapted to produce a signal proportional to the thickness of a sheet material. The device also may employ a proximity detector between rollers conveying the sheets.
I have found that the art represented by the above demonstrates a lack of recognition of the need for a device which measures the thickness of a recording medium, by means of light intensity, and the thickness of a stack of recording media so as to apprize a user with the number of sheets available.
None of the above references, taken alone or in combination, are seen as teaching or suggesting the presently claimed device for calculating sheet number in a sheet feeder and method for calculating same.